diff --git a/src/__tests__/backend-conformance.test.ts b/src/__tests__/backend-conformance.test.ts
index d7824191e..c460aaf52 100644
--- a/src/__tests__/backend-conformance.test.ts
+++ b/src/__tests__/backend-conformance.test.ts
@@ -345,10 +345,11 @@ describe("backend conformance — finalizePartsIntoState", () => {
 // ── Conformance: delivery routing ──────────────────────────────────────────
 
 describe("backend conformance — routeDelivery", () => {
-  it("returns the same route for both backends given equivalent state", async () => {
-    // Text-part route
+  it("returns the same route for all three remote-server backends given equivalent state", async () => {
+    // Text-part route — Kilo / OpenCode / Codex all use shared routeDelivery
     const stateA = createStreamState();
     const stateB = createStreamState();
+    const stateC = createStreamState();
     const kiloDecision = await routeDelivery({
       backendLabel: "Kilo",
       chatId: "c",
@@ -361,38 +362,58 @@ describe("backend conformance — routeDelivery", () => {
       state: stateB,
       responseText: "Hello",
     });
+    const codexDecision = await routeDelivery({
+      backendLabel: "Codex",
+      chatId: "c",
+      state: stateC,
+      responseText: "Hello",
+    });
     expect(kiloDecision.route).toBe(opencodeDecision.route);
+    expect(kiloDecision.route).toBe(codexDecision.route);
     expect(kiloDecision.chars).toBe(opencodeDecision.chars);
+    expect(kiloDecision.chars).toBe(codexDecision.chars);
 
     // Tool route
-    const stateC = createStreamState();
-    Object.assign(stateC, { deliveredTextNorms: ["delivered"] });
-    const stateD = createStreamState();
-    Object.assign(stateD, { deliveredTextNorms: ["delivered"] });
+    const toolStateA = createStreamState();
+    Object.assign(toolStateA, { deliveredTextNorms: ["delivered"] });
+    const toolStateB = createStreamState();
+    Object.assign(toolStateB, { deliveredTextNorms: ["delivered"] });
+    const toolStateC = createStreamState();
+    Object.assign(toolStateC, { deliveredTextNorms: ["delivered"] });
     const kT = await routeDelivery({
       backendLabel: "Kilo",
       chatId: "c",
-      state: stateC,
+      state: toolStateA,
       responseText: "ignored",
     });
     const oT = await routeDelivery({
       backendLabel: "OpenCode",
       chatId: "c",
-      state: stateD,
+      state: toolStateB,
+      responseText: "ignored",
+    });
+    const cT = await routeDelivery({
+      backendLabel: "Codex",
+      chatId: "c",
+      state: toolStateC,
       responseText: "ignored",
     });
     expect(kT.route).toBe(oT.route);
+    expect(kT.route).toBe(cT.route);
     expect(kT.route).toBe("tool");
   });
 
-  it("uses backend label in synthetic-error message prefix", async () => {
+  it("uses backend label in synthetic-error message prefix (all three remote-server backends)", async () => {
     const kiloMessages: string[] = [];
     const opencodeMessages: string[] = [];
+    const codexMessages: string[] = [];
 
     const stateA = createStreamState();
     Object.assign(stateA, { syntheticError: "boom" });
     const stateB = createStreamState();
     Object.assign(stateB, { syntheticError: "boom" });
+    const stateC = createStreamState();
+    Object.assign(stateC, { syntheticError: "boom" });
 
     await routeDelivery({
       backendLabel: "Kilo",
@@ -414,8 +435,19 @@ describe("backend conformance — routeDelivery", () => {
       },
     });
 
+    await routeDelivery({
+      backendLabel: "Codex",
+      chatId: "c",
+      state: stateC,
+      responseText: "",
+      onTextBlock: async (text) => {
+        codexMessages.push(text);
+      },
+    });
+
     expect(kiloMessages[0]).toBe("⚠️ Kilo: boom");
     expect(opencodeMessages[0]).toBe("⚠️ OpenCode: boom");
+    expect(codexMessages[0]).toBe("⚠️ Codex: boom");
   });
 });
 
diff --git a/src/backend/codex/factory.ts b/src/backend/codex/factory.ts
index d75b4edb8..ec16ea7d9 100644
--- a/src/backend/codex/factory.ts
+++ b/src/backend/codex/factory.ts
@@ -15,6 +15,7 @@ import { log } from "../../util/log.js";
 import { initCodexAgent } from "./init.js";
 import { handleMessage as codexHandleMessage } from "./handler.js";
 import { runOneShotAgent as codexRunOneShotAgent } from "./one-shot.js";
+import { resetState as resetCodexState } from "./state.js";
 import {
   resolveModel,
   getModelInfo,
@@ -48,7 +49,18 @@ const codexFactory: BackendFactory = {
       backendLabel: "Codex",
     };
 
-    return { backend };
+    return {
+      backend,
+      // Cleanup: drop the cached Codex instance + state. The Codex
+      // SDK's instances are stateless from our perspective (each
+      // `runStreamed` spawns a fresh subprocess), so there's no
+      // long-running server to stop — clearing module-scoped state
+      // is enough for hot-reload + test isolation.
+      cleanup: () => {
+        resetCodexState();
+        log("bot", "Codex backend cleaned up");
+      },
+    };
   },
 };
 
diff --git a/src/backend/codex/handler.ts b/src/backend/codex/handler.ts
index 2e9329827..5a4ee3121 100644
--- a/src/backend/codex/handler.ts
+++ b/src/backend/codex/handler.ts
@@ -122,6 +122,7 @@ export async function handleMessage(
   // pass through whatever the chat settings hold (default `gpt-5-codex`).
   const chatSettings = getChatSettings(chatId);
   const activeModel = chatSettings.model ?? config.model ?? CODEX_DEFAULT_MODEL;
+  log("agent", `[${chatId}] Codex model resolved: ${activeModel}`);
 
   // First-turn system-prompt rebuild + Codex-specific delivery suffix.
   const systemPrompt = prepareSystemPrompt({